XVI PREFACE. 



the bricks and tiles, it becomes dry, and quite 

 incapable of affording any nourishment to the 

 plants. 



The limited space in which the plants are 

 confined in their growth by brick pits, is also a 

 very great objection to this mode of culture. 

 That they derive their chief support from the 

 extremity of the roots must be obvious to every 

 one, and if these are concentred in the middle 

 of the bed, and thereby rendered incapable of 

 expanding over the flues as in the dung bed, 

 they must be certainly deprived of that vigour 

 which is natural to them from a free and unin- 

 terrupted growth, and where they experience 

 the whole of the benefit that can arise from the 

 bed in which they are placed. In short, the 

 dung bed in so many instances is superior to 

 brick pits, that competitiou in the culture of 

 either the cucumber or melon by the latter plan 



